The present invention relates to a hybrid golf club head of a metal part and an FRP part
Wood-type hollow golf club heads composed of an open-front main body made of a fiber-reinforced plastic and a metal face plate of which outside perimeter is fixed to the main body so as to close the front opening of the main body have been proposed for example as disclosed in US patent application publication US 2003/207726 A1.
In such a structure, as the fiber-reinforced plastics are generally smaller in the specific gravity than the metal materials, the design freedom of the weight distribution of the head is increased. Therefore, the design freedom of the position of the center of gravity of the head is also increased, and it is possible to adjust the center of gravity to a low position as desired. But, when the ball is hit on the metal face plate, the shocks and vibrations thereof concentrate in the junction at the perimeter of the face plate. Therefore, the junction becomes a week point. In particular, as shown in FIG. 11, when the face plate (a) is provided with a turnback (a1), and the turnback (a1) is inserted in a slit (s) formed on the front of the FRP main body (b), cracks are liable to occur at the bottom of the slit confronting the rear end of the turnback (a1).